1. Field of the Invention
The present invention relates to a semiconductor device inspection apparatus and inspection method which inspect an LSI (Large Scale Integration) as a semiconductor device or a bare LSI (bare chip), and, more particularly, to a semiconductor device inspection apparatus and inspection method which are suitable for inspection of an LSI, a bare chip and a wafer which have narrow electrode pitches.
2. Description of the Related Art
Conventionally, a semiconductor device is inspected by acquiring electric contact between the semiconductor device as an inspection target and an inspection substrate by letting probes contact the external terminals of the semiconductor device. An inspection apparatus is available on the market under the name of a wafer prober. An inspection apparatus which deals with adjustment of the parallelism and the influence of vibration at the time of operating the XY stage, which are the issues of the former conventional inspection apparatus to be cleared, is described in Japanese Patent Laid-Open No. 330960/1997 (Patent Document 1). An inspection stage and an inspection apparatus which overcomes the unstable contact caused by tilting of an inspection-target mount table when a semiconductor device to be inspected whose pin quantity is increased is described in Japanese Patent Laid-Open No. 2000-26082 (Patent Document 2). The specifications of a prober available from a prober maker is given in Accretech Product Catalog UF200S (Non-patent Document 1). Those prior arts will be discussed below.    (1) Inspection Apparatus Described in Japanese Patent Laid-Open No. 330960/1997 (Patent Document 1)
Patent Document 1 describes an inspection apparatus which detects the parallelism of a test head and an inspection-target mount table and adjusts the parallelism to acquire stable contact between probe needles and the electrodes of the inspection target and eliminates the influence of positional misalignment by eliminating the influence of vibration at the time of executing step feeding.    (2) Inspection Stage and Inspection Apparatus Described in Japanese Patent Laid-Open No. 2000-26082 (Patent Document 2)
Patent Document 2 describes an inspection stage and inspection apparatus which provide an elevation unit for a inspection target with a mechanism for controlling the elevation position and means for detecting the parallelism so that the tilting of an inspection-target mount table caused when the number of pins of a probe card is increased can be detected and corrected, thus making it possible to always keep the inspection-target mount table horizontal.    (3) Prober Described in Accretech Product Catalog UF200S (Non-patent Document 1)
This document is the catalog of a currently available prober or an inspection apparatus for an IC chip formed on a wafer and describes that the adequate wafer size is 5 to 8 inches and the general precision is within 4 μm.
With regard to the LSI mounting technology, at present, people are paying attention to, and making great efforts on, the development of the mounting technology of the third generation and turning it into products, as typified by stacked CSP (Chip Size Package) or the like. To realize higher integration and faster transfer, it will become necessary in the near future to make a breakthrough on bare chips based on the third generation mounting technology. According to the JEITA 2001 mounting technology road map, the then expected electrode pitch will be reduced to 20 μm by the year 2010. To make practical use of the LSI mounting technology of devices having such super fine electrodes of 30 μm or less, it is extremely important to inspect devices and sort out good devices at the stage of a wafer or bare chips. To achieve it, an inspection apparatus should be guaranteed with the precision of 1 μm or less. As the achievement involves the development of fine probes, it requires an inspection apparatus which can both measure the basic characteristics of probe needles and the originally intended wafer inspection. From the above viewpoints, the prior arts bring about the following problems.
The inspection apparatus described in Japanese Patent Laid-Open No. 330960/1997 or the first prior art is so designed as to be moved and positioned with respect to the XYZ and θ directions at the time of inspection and be moved mainly in the Y direction step by step by each IC chip to make the electrode pads of each IC chip electrically contact the probe needles and inspect IC chips one by one, as mentioned in paragraph 0013 of the specification discussing one embodiment. The contact to the first IC chip is made by picking up the images of the probe needles and the inspection apparatus or the inspection target by means of a camera, computing their positions from the picked-up images and making corrections. Thereafter, contact marks are observed with the camera and X- and Y-directional offset values are input to make the contact to the center of each electrode of the inspection target. Then, the IC chips on the entire wafer are probed and inspected through a constant step feeding operation.
This inspection apparatus has the following shortcomings.
(1) As step feeding is carried out with the first positioned chip in a lot taken as a reference, the positional precision for the subsequent IC chips is determined by the initial θ-directional error and the stage precision in the feeding direction. Accordingly, the precision of an IC chip distant from the first chip becomes lower, making it difficult to probe electrodes of a fine pitch of 40 μm or less.
(2) As the elevation unit for the Z axis uses a stepping motor using a ball screw, upward movement by a given amount is merely designed, making the actual amount of stage movement unclear, and the precision is as large as several micrometers. This does not guarantee the adequate overdrive amount (which is the pressing amount after the probe needles contact the electrodes of the inspection target and will be hereinafter referred to as “OD amount”), which may adversely affect the contactability.
(3) Because the inspection apparatus does not have a load detecting mechanism, a contact start point cannot be defined clearly, making it hard to measure the basic characteristics of the probe needles.
(4) As the elevation unit does not have a stopper mechanism, the probe card should be provided with a stopper.
(5) In case where a semiconductor device abuts on the stopper of the probe card and stops, the semiconductor device may be damaged.
The inspection apparatus described in Japanese Patent Laid-Open No. 2000-26082 or the second prior art inspects a wafer by repeating index feeding of the wafer after alignment of the wafer with a probe card is performed, as mentioned in paragraph 0020 of the specification discussing the means for solving the problems of the second prior art. As positions in upward and downward movements can be detected by a linear sensor attached to an elevation unit, the problem (2) of the first prior art is overcome. Although the parallelism of a wafer chuck is detectable, the second prior art fails to describe any specific means of detecting the parallelism of the wafer chuck and the probe card. The second prior art therefore still has the problems (1), (3), (4) and (5) of the first prior art.
It is mentioned that the prober described in Accretech Product Catalog UF200S or the third prior art has the general precision of 4 μm or less as the main specification. The third prior art however fails to specifically describe the mechanism portions and operation of the prober and is thus assumed to take the structure of the first prior art or the second prior art. The third prior art therefore also has the problems (1) to (5).
In short, the conventional semiconductor device inspection apparatuses have the problems that positioning is done through constant step feeding after inspection of the first IC chip, there is insufficient consideration given on the environment which influences the precision, such as vibration, there is no contact detecting mechanism, there is no load detecting mechanism, it is difficult to probe fine-pitched electrodes, it is not possible to clearly define a contact start point, making it hard to secure the adequate OD amount in every inspection area, it is difficult to measure the basic characteristics of the probe needles and the elevation mechanism does not have a stopper mechanism.